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A platform for research: civil engineering, architecture and urbanism
Dimensional stability and moisture-induced strains in spruce cross-laminated timber (CLT) under sorption/desorption isotherms
Highlights Deformation of spruce CLT and its wood layers under sorption and desorption cycles are different. The dimensional changes of CLT panels above FSP may be neglected. Temperature affects CME and CMC of CLT panels. Mismatch of CTE and CME (or CMC) leads to significant stresses. Mismatch of CTE and CME of wood layers can affect integrity of CLT panels.
Abstract The paper presents a comprehensive experimental–numerical study on dimensional stability of spruce CLT panels and provides new insights into understanding the effect of mechanical properties of wood layers on moisture-induced strains. Deformations in Norway spruce CLT as well as their wood layers were studied in two orthogonal planes under sorption and desorption cycles. Coefficients of Moisture Expansion (CME), Coefficient of Moisture Contraction (CMC), as well as Coefficient of Thermal Expansion (CTE) were determined using dimensional measurements at 15° and 50℃. A 3-D nonlinear finite element (FE) model was developed to better understand the effect of glue and wood mechanical properties, as well as their CME and CTE on two CLT cross-sections. Unlike previous studies, the glue layers have been modelled as thin physical layers bonding wood layers. Hence, the effect of glue lines on the performance of CLT panels can be elucidated quantitatively. Results demonstrated good agreement between the FE model predictions of moisture-induced strains and the experimental data under both sorption and desorption isotherms when the wood moisture content is below fibre saturation point (FSB). Discrepancies between experiments and the model were noted at moisture contents above FSB. Such discrepancies may be attributed to measurement inaccuracies at small scale, the annual ring patterns, uncertainties in material properties, glue penetration into wood cell walls, as well as imperfect bonding at the glue lines. Results highlighted the significant effect of the mismatch between CTE and CME (or CMC) of wood in different directions on the development of stresses and consequently delamination, and perpendicular to grain failure in CLT panels subjected to extreme humidity levels.
Dimensional stability and moisture-induced strains in spruce cross-laminated timber (CLT) under sorption/desorption isotherms
Highlights Deformation of spruce CLT and its wood layers under sorption and desorption cycles are different. The dimensional changes of CLT panels above FSP may be neglected. Temperature affects CME and CMC of CLT panels. Mismatch of CTE and CME (or CMC) leads to significant stresses. Mismatch of CTE and CME of wood layers can affect integrity of CLT panels.
Abstract The paper presents a comprehensive experimental–numerical study on dimensional stability of spruce CLT panels and provides new insights into understanding the effect of mechanical properties of wood layers on moisture-induced strains. Deformations in Norway spruce CLT as well as their wood layers were studied in two orthogonal planes under sorption and desorption cycles. Coefficients of Moisture Expansion (CME), Coefficient of Moisture Contraction (CMC), as well as Coefficient of Thermal Expansion (CTE) were determined using dimensional measurements at 15° and 50℃. A 3-D nonlinear finite element (FE) model was developed to better understand the effect of glue and wood mechanical properties, as well as their CME and CTE on two CLT cross-sections. Unlike previous studies, the glue layers have been modelled as thin physical layers bonding wood layers. Hence, the effect of glue lines on the performance of CLT panels can be elucidated quantitatively. Results demonstrated good agreement between the FE model predictions of moisture-induced strains and the experimental data under both sorption and desorption isotherms when the wood moisture content is below fibre saturation point (FSB). Discrepancies between experiments and the model were noted at moisture contents above FSB. Such discrepancies may be attributed to measurement inaccuracies at small scale, the annual ring patterns, uncertainties in material properties, glue penetration into wood cell walls, as well as imperfect bonding at the glue lines. Results highlighted the significant effect of the mismatch between CTE and CME (or CMC) of wood in different directions on the development of stresses and consequently delamination, and perpendicular to grain failure in CLT panels subjected to extreme humidity levels.
Dimensional stability and moisture-induced strains in spruce cross-laminated timber (CLT) under sorption/desorption isotherms
Chiniforush, A.A. (author) / Ataei, A. (author) / Valipour, H.R. (author) / Ngo, T.D. (author) / Malek, S. (author)
2022-09-19
Article (Journal)
Electronic Resource
English
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